The invention relates to a robot wrist.
Modern engineering industry places increasingly heavy demands on the orientation capacity of the arm and wrist of a robot. A plurality of different arm and wrist designs are known which enable a tool to be operated in different positions within a working area. In order for the arm and the wrist to be capable of being operated in the desired manner, a plurality of axes and gears rotating inside the arm and the wrist, and sometimes also separate motors, are additionally required. These units are relatively space-demanding and if, in addition, for example, the wrist is to accomodate hydraulic and/or electric cables for the supply of power to the control carried by the wrist, it may be necessary to construct a relatively thick wrist. This, however, reduces the ability of the robot to operate in confined spaces. In prior art devices, for example according to U.S. Pat. No. 4,690,012 the drive motor for the tool attachment is a fully normal motor mounted at the side of the tubular tool attachment which is driven via a gear. The gear may also to a certain extent occupy lateral space.
The invention aims at developing a robot wrist which, on the one hand, is of relatively slim design and, on the other hand, provides ample through-going inner space to allow the passage of supply and/or communication means through the wrist.
To achieve this aim the invention describes a robot wrist wherein the gear and the motor thereof are built together to form a tubular motor-gear package, which is arranged concentrically with the member, for example a tool attachment, driven by it. Both, the gear wheels and the rotor, are made tubular in order to create a channel for supply and/or communication means. Such means may comprise, for example, hydraulic and/or electric cables, glass fibre cables or mere light or laser light beams. At a given diameter of the channel, the the outer diameter of the wrist will be smaller than if the motor and/or the gear were arranged adjacent to the channel.
The invention will now be described in greater detail, by way of example, with reference to the accompanying drawings.